The only tip I can give is to get all of your non-metal parts before you so much as remove a spark plug. Some parts are discontinued. If it´s a matter of a gasket, you can probably make one. But things like the balancer dampers can´t be made at home. If you know what parts you have, you know how far into the engine you can go. For metal parts such as rings and valve guides, you won´t know about them until you inspect them. If the metal part is no longer available, you can reverse engineer it and have a shop fabricate a new part. Who knows, you may get a high-performance AlSi alloy piston and increase the top speed from 85mph to 100mph, sorry I don´t know the conversion factor (American you know, we keep holding on to the Imperial system).